| 摘要 |
PURPOSE:To impart excellent performance in magnetic field uniformity to a coil system, by constituting two circular coils having a fan shaped cross section. CONSTITUTION:The circular coils 3 and 4, which have the fan shaped cross section, face each other. The directions of currents are the same. It is natural to describe the coil system having said cross section by polar coordinates. Their magnetic fields are expanded by r<2n> (wherein r is the distance between an observing point P and an original point O, and n is an integer) and a Legendre's function. Since the expansion equation and the coordinate system which describes the coil shape are the same, the magnetic uniformity is improved in a spherical space having a constant radius. Furthermore the volume occupied by the coil system is reduced. |
